1. Field of the Invention
The invention relates to a battery pack. More particularly, the invention relates to a battery pack in which a plurality of single cells and a plurality of spacers are juxtaposed in a predetermined direction, and a juxtaposed body of these single cells and spacers (i.e., a body formed by these juxtaposed single cells and spacers) is banded together while being pressed in the predetermined direction. Each of the single cells is a non-aqueous electrolyte cell in which a rolled electrode body that is flatly rolled is housed in a flat case.
2. Description of Related Art
Japanese Patent Application Publication No. 2014-154484 (JP 2014-154484 A), for example, describes a battery pack in which a plurality of flat single cells and a plurality of spacers are alternately juxtaposed. Each of the single cells is a non-aqueous electrolyte cell in which an electrolyte and a rolled electrode body are housed in a flat case. Each of the spacers is made of an insulating body, and is spaced between adjacent single cells in order to insulate the cases of adjacent single cells and inhibit a rise in temperature of the single cells. With the battery pack described in JP 2014-154484 A, pressure in a predetermined direction is applied to the juxtaposed body of single cells, and in each single cell, the rolled electrode body inside the flat case is sandwiched from both sides by a pair of side plates of the flat case, in order to prevent the rolled electrode body from vibrating inside the flat case when the battery pack vibrates. To simplify the description, the predetermined direction will hereinafter be referred to as the “juxtaposing direction”. The pressure in the juxtaposing direction is applied to the rolled electrode body via the spacer and the case side plate. With the battery pack described in JP 2014-154484 A, a plurality of grooves are provided in a contact surface of the spacer that contacts the single cell in order to further inhibit a rise in the temperature of the single cell. A cooling medium (air) flows through these grooves to inhibit a rise in the temperature of the single cell (see paragraph [0060] and FIG. 9 in JP 2014-154484 A). The battery pack in JP 2014-154484 A is designed to be mounted in an electric vehicle, as a power supply for a running motor. In an electric vehicle, a vibration countermeasure is particularly important.